Question: what did sub-orbital spaceflight mean for the mission that the crew member Alan Shepard was a part of
Paraphrase: What suborbital spaceflight meant for the mission was Alan Shepard's crew member part of
SPARQL (Wikidata):  select distinct ?sbj where { ?sbj wdt:P1029 wd:Q174979 . ?sbj wdt:P31 wd:Q832435 } 
Answer: Mercury-Redstone 3